The calculated distance (air line) between Cologne and Forchies-la-Marche is approximately 120 miles respectively 193 kilometers.
By car or train, the actual journey to Forchies-la-Marche is certainly longer, as only the direct route (as the crow flies) between Cologne and Forchies-la-Marche has been calculated here.
Air line (approximately)
193 kilometers
104 nautical miles